Initial commit of guile support files.
Add guile targets to Makefile.
Add load-relative for guile support.
Make load-relative a procedure instead of a macro.

Load is a procedure in all the supported schemes, unlike `include',
which is a special form in gambit.
Ignore the TAGS file.
Remove invalid eqv? test that was failing in guile.

While it's no doubt permitted for an implementation to return a fresh
closure for every (p1 'type) message, it seems unlikely that it's
required. In fact, guile is smart enough to return the same procedure
object every time, which causes the eqv? test to fail.
Define pp in guile-book.scm.
Pull in SFRI 43 for vector operations.

Vectors are needed in src/chap7g.scm.
Fix error in bounded-display: object? -> Object?.
Update the README to mention guile support.